This application is a 371 of PCT/EP96/03756, filed Aug. 26, 1996.
1. Field of the Invention
The present invention relates to novel polymerizable liquid-crystalline compounds of the formula I EQU Z.sup.1 --Y.sup.1 --A.sup.1 --Y.sup.3 --M--Y.sup.4 --A.sup.2 --Y.sup.2 --Z.sup.2 I
where
Z.sup.1 and Z.sup.2 are radicals containing reactive groups via which polymerization can be effected, PA1 Y.sup.1 -Y.sup.4 are a single chemical bond, oxygen, sulfur, --O--CO--, --CO--O--, --O--CO--O--, --CO--NR--, --NR--CO--, --O--CO--NR--, --NR--CO--O-- or --NR--CO--NR--, where at least one of the groups Y.sup.3 and Y.sup.4 is --O--CO--O--, --O--CO--NR--, --NR--CO--O-- or --NR--CO--NR--, PA1 A.sup.1 and A.sup.2 are spacers having 2 to 30 carbon atoms in which the carbon chain may be interrupted by ether oxygen, thioether sulfur or by nonadjacent imino or C.sub.1 -C.sub.4 -alkylimino groups, PA1 M is a mesogenic group, PA1 R is C.sub.1 -C.sub.4 -alkyl. PA1 --(CH.sub.2).sub.p --, --(CH.sub.2 CH.sub.2 O).sub.m CH.sub.2 CH.sub.2 --, --CH.sub.2 CH.sub.2 SCH.sub.2 CH.sub.2 --, --CH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 --, ##STR3## where m is from 1 to 3, and p is from 1 to 12. PA1 T is a divalent saturated or unsaturated iso- or heterocyclic radical, PA1 Y.sup.5 is a bridge as defined for Y.sup.1 -Y.sup.4 ; --CH.sub.2 --O--; --O--CH.sub.2 --; --CH.dbd.N--, --N.dbd.CH-- or --N.dbd.N--, PA1 r is 0, 1, 2 or 3, where the radicals T and Y.sup.5, in the case where r is &gt;0, may be identical or different. PA1 r is preferably 1 or 2. PA1 T is different radicals ##STR14## (unsaturated isocyclic) and ##STR15## (saturated heterocyclic), r is 1, or ##STR16## where in formula Ia Y.sup.5 is a single chemical bond, PA1 T is different radicals ##STR17## (unsaturated isocyclic) and ##STR18## (unsaturated heterocyclic), r is 1. PA1 Z.sup.3 are radicals containing reactive groups via which polymerization can be effected, PA1 Y.sup.6 -Y.sup.8 are a single chemical bond, oxygen, sulfur, --O--CO--, --CO--O--, --O--CO--O--, --CO--NR--, --NR--CO--, --O--CO--NR--, --NR--CO--O-- or --NR--CO--NR--, where at least one of the groups Y.sup.7 and Y.sup.8 is --O--CO--O--, --O--CO--NR--, --NR--CO--O or --NR--CO--NR--, PA1 A.sup.3 is a spacer having 2 to 30 carbon atoms in which the carbon chain may be interrupted by ether oxygen, thioether sulfur or by nonadjacent imino or C.sub.1 -C.sub.4 -alkylimino groups, PA1 P.sup.1 are radicals selected from the group of hydrogen, C.sub.1 -C.sub.30 -alkyl, C.sub.1 -C.sub.30 -acyl, C.sub.3 -C.sub.8 -cycloalkyl unsubstituted or substituted by one to three C.sub.1 -C.sub.6 -alkyl and where the carbon chain of the alkyl, acyl and cycloalkyl radicals may be interrupted by ether oxygen, thioether sulfur or by nonadjacent imino or C.sub.1 -C.sub.4 -alkylimino groups. ##STR20## PA1 P.sup.2,P.sup.3 are radicals selected from the group of hydrogen, C.sub.1 -C.sub.30 -alkyl, C.sub.1 -C.sub.30 -acyl, C.sub.3 -C.sub.8 -cycloalkyl unsubstituted or substituted by one to three C.sub.1 -C.sub.6 -alkyl, and where the carbon chain of the alkyl, acyl and cycloalkyl radicals may be interrupted by ether oxygen, thioether sulfur or by nonadjacent imino or C.sub.1 -C.sub.4 -alkylimino groups, PA1 Y.sup.9, Y.sup.10 are a single chemical bond, oxygen, sulfur, --O--CO--, --CO--O--, --O--CO--O--, --CO--NR--, --NR--CO--, --O--CO--NR--, --NR--CO--O-- or --NR--CO--NR--, where at least one of the groups Y.sup.9 and Y.sup.10 is --O--CO--O--, --O--CO--NR--, --NR--CO--O or --NR--CO--NR--, PA1 M is a mesogenic group. PA1 (The terminal dashes in the above formulae indicate the free valencies.) PA1 a) 1-98 mol %, PA1 b) 1-98 mol %, PA1 c) 0.01-90 mol %,
The present invention furthermore relates to liquid-crystal compositions comprising these compounds and possibly one or more chiral compounds, to a process for preparing the novel liquid-crystalline compounds, to a process for coating substrates with the novel compounds or liquid-crystal compositions, and to the use of the compounds or liquid-crystal compositions for producing optical display devices, as cholesteric liquid-crystalline colorants, and to pigments obtainable by polymerizing the liquid-crystal compositions and subsequently comminuting.
2. Description of the Background
Numerous compounds are not converted directly into the liquid, unordered state on warming from the crystalline state with a defined close and long-distance ordering of the molecules, but instead pass through a liquid-crystalline phase, in which, although the molecules are mobile, the molecule axes form an ordered structure. Elongate molecules frequently form nematic liquid-crystalline phases which are characterized by an alignment long-distance ordering owing to parallel arrangement of the long axes of the molecules. If a nematic phase of this type contains chiral compounds, a so-called cholesteric phase forms, which is characterized by a helical superstructure of the long axes of the molecules. The chiral compound here can be the liquid-crystalline compound itself or it can be added to a nematic liquid-crystalline phase as a chiral dope.
Liquid-crystalline materials have remarkable optical properties based on thier anisotropic ordered state. However, the liquid-crystalline ordered state only occurs in a limited temperature range. The temperature range in which liquid-crystalline phases occur is frequently far above the desired use temperature or extends only over a small temperature range.
There are various ways of obtaining and fixing the ordering structures desired for the material properties, even in the solid state. In addition to glass-like solidification on cooling from the liquid-crystalline state, there is also the possibility of copolymerization into polymeric networks or, if the liquid-crystalline compounds contain polymerizable groups, polymerization of the liquid-crystalline compounds themselves.
Polymerizable liquid-crystalline compounds are described, for example, in EP-A 261 712 and in WO 93/05436, WO 95/24453, WO 95/24454 and WO 95/24455. In polymeric form, these compounds usually have the requisite mechanical stabilities, but are in some cases unsatisfactory owing to the temperature level of their liquid-crystalline phases and the temperature range of these phases.